Before actually ordering service, there are several things you may want to
explore. Please note, that there are many ways any given telco might
decide to handle qualification and installation procedures. Much of what
is described in this section, is how it is commonly done in the U.S.

In many parts of the world, there is no choice on who you get DSL from: your
friendly local telco, of course! They own the copper wires, and thus they
hold all the cards.

However, in the U.S. de-regulation has opened this up somewhat. Beyond the
obvious consideration of price, there are reasons to investigate which
alternate providers may be offering DSL services in your area. The large
Telephone companies are everywhere, and may advertise the most. But
increasingly smaller ISPs and independents are getting into the act. This has
created some diversity in the DSL marketplace. A good thing of course, but
possibly creating a little confusion too. Conversely, in areas where there
is only one choice, then we have no choice but to accept whatever service
is being offered.

If your telco has a monopoly on phone service and DSL, you may skip the
rest of this section. And probably the next few sections. They will probably
control the installation and qualification processes, and you just wait
for them to get finished.

Not all DSL services are alike. Just because two local companies are offering
"ADSL", does not mean that necessarily there is much in common
at all. In fact, there are potentially a number of factors that make one ADSL
provider's service significantly different from another's. Some things to
consider:

Speed vs Price.

What hardware is provided, i.e. modem or router. It is best if this is
external ethernet in either case.

The ISP's Network architecture. PPPoX? Static IP? Servers allowed?

Is it an "always on" service, at least theoretically? Are
there supplemental usage fees, or idle timeouts?

Linux friendly, Linux hostile, or Linux agnostic? This is not as much of
a problem as it used to be in most areas. Some providers are still very
restrictive on allowing "servers", and possibly even
LAN connections. Buyer beware. Talk to other users, and read their
TOS (Terms of Service) to get a feel for their attitude.

Quality of service. How is news, mail, etc.? News particularly seems
to be inconsistent with low-end broadband providers. Probably because
of the dramatic increase in binary news content, which is compounded by the
higher bandwidth and increased usage of such groups.

Once you have chosen a provider, and ordered service, the next step is for
the telco to "qualify" your loop. This essentially means testing
your line to make sure it can handle the DSL signal, and possibly what level
of service may be available to you. This may take some time, especially if
the telco encounters problems with the loop. If no problems are found during
this phase, then possibly there will be a one to three week wait for the
installation. YMMV.

After the telco has qualified the loop and readied their end of the
connection, the next step is installation of the necessary components at the
customer's end of the connection: wiring modifications, splitter or filters,
and, of course the modem and any necessary software.

You may or may not have a choice on how the installation is done, or who
does it. This is totally at the discretion of the provider. In much of the
world, this is done by the telco, and there is little flexibility. Many
providers in the U.S. offer a "self install" option where you do
all the work. In this scenario, the provider will send a kit in order to save
them from sending a tech, and thus reducing cost. Typically, self install
kits will include microfilters for the POTS (Plain Old Telephone Service)
or ISDN (where ADSL over ISDN is used) phone jacks, the modem (and
maybe a NIC), and a CDROM with drivers, etc. on it. In some cases, a splitter
may be included instead of microfilters. In any case, some type of filtering
is necessary on the non-DSL lines. If not the noise generated by the DSL
signal may interfere with regula telco devices such as phones and answering
machines.

The other possibility is for the provider to do the installation. Again, this
may be your only option. Obviously, the cost is higher here, but it may have
the advantage of having a trained tech do any wiring. There is also a better
chance of getting a "splittered" installation with this option
(a good thing!). Another benefit is that if something is wrong with the line,
or the telco has not provisioned the line properly, an on-site tech may be
able to help sort out certain kinds of problems quickly.

The self-install kit should come with full instructions, regardless of whether
the installation will be splittered or filtered. So we won't go into much
detail on this aspect.

There are various wiring schemes depending on how your service is being
provided, who is providing it, and which DSL service is being provided.
If your telco is performing the installation, you may skip this section.

Dedicated Line. Some DSLs require a dedicated, or
"dry", wire pair, e.g. IDSL. This means a separate, physical
line without dial-tone for DSL and Internet connectivity. Also, DSL
services from CLECs (independent telcos like Covad), may use a
dedicated line, depending on their line sharing agreement with the local
incumbent carrier. (Instead the CLEC will actually lease a loop from the
ILEC.) On your end, this simply means using one of the unused wire pairs
in the telco wire bundle, and connecting it to the DSL jack.

Shared Line with Splitter. For DSLs like ADSL, that
are provided over the same line as regular voice service, the signal
must be filtered somehow so that voice services are not adversely effected.
Installing a splitter splits the line into two pairs, and filters the DSL
signal from one of them. This results in a inside wiring scheme where DSL
goes to only one jack, and then regular voice type service to all other
jacks. This is considered by many to be a better type of installation than
"splitterless", i.e. with microfilters instead. See below.

Splitters are available from various manufacturers and come in various
shapes and sizes. Some are small enough to fit in the NID itself (sometimes
called SNI, this is the telco phone box on the outside of your house),
while others have a housing as large as the NID itself. Typically this is
mounted near the NID, on the customer's side of the demarcation point.

Shared Line with Filters. Again, for some DSLs that
piggyback on the POTS (or ISDN) line, the signal must be filtered or split at some
point. This is not necessary for g.lite or RADSL however. The other way of
doing this is by placing RJ11 "microfilters" in each phone
jack -- except where the DSL modem will be. These
filters are relatively small, plug-in devices and remove the higher
frequencies associated with DSL. This is obviously much easier since no
tools or wiring is required. This is often what is included in self-install
kits, and is often referred to as a "splitterless"
installation. This is a very common approach in the U.S. Note that
in areas where ADSL over ISDN is provided, filtering is required
also, but the filters themselves are quite different and are not
interchangeable with POTS filters!

Similar microfilters are sometimes used by some telcos to reduce the
excessive "whine" on the line that is produced by some modems.
This is a little different approach as the filter is put on the same
jack as the modem.

Shared Line, Splitterless and Filterless. Some newer
DSLs, like G.Lite, have no adverse effect on regular POTS devices and thus
require no filters or splitters. This would seem to be the wave of the
future. Just plug and play. Though still not very common.

If you are not doing a self-install, then you may skip this section
and move to Configuring Linux. If you are
doing a self-install with microfilters, skip to the
mircofilter section. The following procedures
are meant to illustrate the wiring process. Please note that your procedures
may be different at your location. Make sure you follow any warnings or
safety instructions provided, that you RTFM, and that you are familiar with
telco wiring procedures.

The first step will be to wire up the connections from your provider. Identify
the line on which service will be installed, and the locations of your
splitter and DSL jack(s). (For perhaps a better wiring scheme, see the
Homerun section immediately below.)

Be aware that typical telco wire has more than one pair per bundle. Often,
two pairs, but sometimes more. If you have but one phone line, the other
pair(s) are unused. This makes them available for use with wiring for DSL.
Wire pairs are color coded for easy identification. SDSL and IDSL require a
dedicated, or "dry", pair. If an unused pair is available, then
no real re-wiring is required. It is just a matter of re-wiring an existing
jack for the correct pair of wires, and attaching the modem.

" I would not use microfilters if I lived across the street from my CO. A
splitter is the only way to go.
"

--A retired BellSouth ADSL installer

The optimum method of wiring for the DSL modem is sometimes
called a "homerun". It is called this because it is one,
straight shot from the splitter to the modem's DSL jack. What this does is
bypass the existing inside wiring altogether, and any problems that might be
lurking there -- like a corroded connection somewhere on a voice jack. Inside
wiring deficiencies can cause a degradation of the DSL signal.

This also allows you to route the cable to avoid any potential
RFI (Radio Frequency Interference) sources. RFI anywhere in the
circuit can be a DSL killer. Routing the cable away from items that
may have electric motors, transformers, power supplies, high
intensity lighting fixtures, dimmer switches and such, is a smart way
to go. And you are also less likely to have a failing microfilter
cause problems -- one potential point of failure instead of several. You can
also use a better grade of cable such as CAT 5.

If your existing installation is "splitterless" (i.e. using
microfilters) now, converting to a homerun will entail purchasing a splitter.
And, of course, will also mean some new wiring will need to be run.
Microfilters also add to the effective loop length -- as much as 700 ft per
filter in some cases! So if you have several microfilters installed, and your
sync rate or distance is marginal, eliminating these filters may result in a
significant improvement.

A poor man's splitter can be rigged by using a microfilter inside the NID.
This is not "by the book", but seems to work just fine for many.

If you have the splitterless design (i.e. using "microfilters")
or a dedicated line, you may skip this part.

The splitter will typically consist of two parts, the splitter and a small
outdoor housing. Mount the splitter and accompanying housing per the telco's
instructions at the Network Interface Device (NID) point (also sometimes
called the SNI or ONI), usually the side of your house where the phone line
is located. Put it on your side of the NID. The phone company may need
to access the splitter for maintenance, so its advisable to locate it on the
outside where they can get at it, but outside is not absolutely
necessary.

The wire bundle should have at least two separate wire pairs. The splitter
takes one pair, and separates the signal onto two pairs. One pair in the
bundle will then go to all phone jacks, and the other to the modem's DSL wall
jack. So connect the incoming telco line to the LINE side of the splitter.
Then wire the inside pair for your telephone to the VOICE, and your inside
wire pair for the modem to DATA.

Checkstep At this point, you should be able
to pull dial tone off the voice side of the splitter. If this doesn't work,
then you've wired it wrong. You can also plug the modem into the test jack in
the NID box (most should have this). Plug in the modem's power cord, and
if the line is provisioned correctly, you should "sync" in less
than a minute. This test only requires the modem. (Internal and USB modems
will require a driver to be loaded before syncing. This would mean having the
computer there too.)

Wire the DSL wall jack (RJ11) at your computer location, which should already
be connected to the DATA side of the splitter. The specifics differ for each
situation, but basically you will have a wire pair that you will connect to
the DSL jack. Make sure you read the directions, as the
DSL-RJ11 wiring may be different for phones and DSL jacks.
AND -- different modems may expect the signal on
different pairs -- most on the inside pair, but some on the outside pair.

Pretty much a no-brainer here. If you are doing a
"splitterless", self-install installation, then install the
provided microfilters in all phone jacks except the one
where the DSL modem will be connected. Don't forget devices like fax machines
and analog modems. The filters filter out the higher DSL frequencies and will
keep the DSL noise from interfering with POTS (or ISDN) equipment.

Warning!
Alarm systems can present various problems, depending on the type of alarm
and how it is installed. This may require telco help for proper installation
so the one does not interfere with the other. Common microfilters tend not to
work because most alarm boxes use a different size jack. Filters are now
available just for alarm boxes, though traditionally this has been handled
with a splitter type installation.

To install, connect the modem's (or router's) power cord, and connect
the phone line between the DSL wall jack and the modem. This cable should be
provided. If not, a regular phone cord will suffice. With the ethernet
interfaced modems, you may also connect the ethernet cable between the NIC
and the modem (but not really necessary at this point just to verify an
ethernet modem is working).

Checkstep At this point, verify that
the modem syncs with the telco's DSLAM signal. Most modems have a
green LED that lights up when the signal is good, and red or orange
if not in sync. The modem's manual will have more details on the
LEDs. If it doesn't sync, then check your wiring, or make sure that
the DSL signal is being sent. Do this by calling your telco and
verifying they have activated the service. Or by testing the modem at
the test jack on the NID (see above). Note that having dial tone
on the line does NOT confirm the presence of the DSL data signal. And
vice versa -- perfectly possible to have dial tone and no DSL, or DSL
and no dial tone. There should also be no static or noise on the
voice line when everything is installed and functioning properly.

Ethernet modems will, of course, require an ethernet network card.
If you haven't already done so, install the NIC in your Linux machine,
configure the kernel, or load modules, etc., etc. This is sometimes the
biggest stumbling block -- getting the NIC recognized and working. See the
various Linux references for doing this, such as the Ethernet
HOWTO for more information. Also, see the Troubleshooting Section below. This is certainly
something you could conceivably do ahead of time if you already have the NIC.

Be sure the RJ45 cable between the NIC and the modem is now connected. You
can "hot plug" this cable, meaning there is no need to power
down to do this.

We can do a few quick tests now to see if the NIC seems to be functioning
properly. First we'll attempt to bring up the interface. Then we'll see how
well it is responding by pinging it. And lastly use
ifconfig to check for errors:

If "eth0" comes up without errors, and you can
ping it without errors, and ifconfig
shows no errors, we most likely have all our hardware in working order now, and
are ready to start configuring Linux. If not, see the Troubleshooting section below.

Gotcha: A few modems may already be wired as
a 10baseT crossover, and require a direct Category 5 cable for a direct
connection to a NIC, rather than a crossover cable. I lost around 12 hours
figuring this one out, so don't make the same mistake - make sure you RTFM
first.

The physical installation of a USB modem is similar to an ethernet modem.
There is no ethernet card necessary obviously. So connect the phone
line between the DSL wall jack and the modem's DSL port, and attach the
USB cable to the computer's USB port.

USB modems will require vendor and model specific drivers in order to sync
and function properly. Assuming you are using the Alcatel SpeedTouch USB,
this will require both a binary firmware driver available from Alcatel's
driver page: http://www.speedtouchdsl.com/support.htm,
and a separate modem driver.

This driver also supports both PPPoE and PPPoA, though the steps for getting
either to work are quite different. See the
Appendix for more on this modem.